OK so I did my reality checks in my dream and they worked. The only thing is, the moment I questioned my surroundings, I became blind in the dream and then woke up few seconds later but it was actually just a false awakening. Why did this happen?

You questioned your surroundings as you woke "mentally" up . this same waking up caused you to loose the dream you'd been in. So it was the same factor which allowed you to gain awareness to which caused your blindness... a change in your mental/brain state.

To that I say, congratulations! Your subconscious is starting to figure out the difference between dreaming and waking, and when you figure out you're in a dream your brain just doesn't know what to do anymore. I've had so many close calls in regards to lucid dreaming, where the moment of lucidity makes me wake right up, or in the morning all I remember is saying "This is a dream!" but nothing about the dream itself-- while it is frustrating, just remember that you are re-training your brain and it'll take time for the new connections to be made. Keep at it!

"for a dreamer, night's the only time of day..." -Jack Feldman, Santa Fe